Features: 1.Every product has a unique Manufacturing Part Number label on the inner package that proves it has been qualified,which include Part Number,Model Number and inspection date information 2.If you have any questions about the item,please provide us the Manufacturing Part Number for checking,your profits will be guaranteed. 3.The differential gear slipper is made of harder steel metal for durability, smooth performance and low noise. 4.Multiple options: Speed depends on your gear ratio. We offer 3 pinion gears (17T 19T 21T), giving you more choices in gear ratios. Replacement original part number: Replacement for ARA311030. Applicable brands: Replacement for Arrma. Applicable models: Replacement for Arrma Senton 4X4 MEGA550 RC1:10, Replacement for Granite 4X4 MEGA550 RC1:10, Replacement for Typhon 4X4 MEGA550 RC1:10. Specifications: Material: Metal Steel Color: Blue and Silver and Grey Size: 91T Spur Gear Differential: 60x49mm or 2.36"x1.93" (LxDia) 17T pinion: 10x10mm or 0.39"x0.39" (LxDia) 19T pinion: 10x11mm or 0.39"x0.43" (LxDia) 21T pinion: 10x12mm or 0.39"x0.47" (LxDia) Weight: 88g Package include: 1x Differential Gear Slipper 91T 1x Pinion 17T 1x Pinion 19T 1x Pinion 21T 3x Screws